Effect of Level of Ration Intake and Duration of Vitamin A Deficiency Upon Some Biochemical Constituents in Serum, Cerebrospinal Fluid, and Aqueous Humor of Holstein Calves Fed Fixed Carotene Intakes

Abstract

Summary Forty-eight male Holstein calves, averaging 79±6 days of age and 7.2±1.8 β of vitamin A per 100ml of plasma, were fed one of two intakes of a vitamin A depletion ration, 100%, estimated to provide an anticipated weekly gain of approximately 10lb, or 60%, which was six-tenths of the ration allowance of the 100% intake group, for one of two durations, 12-wk or 24-wk, and one of six carotene intakes from artificially dehydrated alfalfa, 10-, 20-, 30-, 40-, 50-, or 60-β per pound of live weight per day. Marked differences between the 60% and 100% intake groups were observed in daily rate of live weight gain, 1.36 vs. 2.08lb, in heart rate, 74 vs. 88 beats per minute, in the QT electrocardiographic interval, 0.364 vs. 0.314sec, and in the systolic index, 0.400 vs. 0.378. These differences in the calves fed the 60% level of ration intake were accompanied by higher concentrations of plasma and liver vitamin A, by slightly lower cerebrospinal fluid pressures, and by an alteration in the protein distribution of serum and cerebrospinal fluid. The latter changes were primarily attributable to decreases in the beta-globulin fraction. Also, slightly lower concentrations of chloride in serum and of sodium and potassium in cerebrospinal fluid occurred in the 60% level of ration intake calves. To maintain equivalent cerebrospinal fluid pressures, calves fed the 60% level of ration intake required 0.74 as much carotene as calves fed the 100% level of ration intake, and to maintain equivalent liver vitamin A stores per unit of live weight, 0.86 as much carotene. Duration of deficiency, either 12-wk or 24-wk, had an inappreciable effect on most of the criteria studied. There was some indication of greater cerebrospinal fluid pressures in the calves fed the three lowest carotene intakes for the 24-wk duration than in comparable calves of the 12-wk grouping, as well as higher serum magnesium and cerebrospinal fluid sodium concentrations. Calves fed the three lowest carotene intakes, deficient as evidenced by elevated cerebrospinal fluid pressures, exhibited greater protein concentrations in serum and cerebrospinal fluid (also slightly greater in aqueous humor but not statistically significant) than did calves fed the highest three carotene intakes, adequate as evidenced by no elevation in cerebrospinal fluid pressures. These increased total protein concentrations were attributable, primarily, to increases in the beta-globulin fraction and to a lesser degree in the gamma-globulin fraction.